title: The influence of stem design on critical squeaking friction with ceramic bearings.
abstract: Ceramic-on-ceramic hip joints have been reported to squeak, a phenomenon that may occur in compromised lubrication conditions. One factor related to the incidence of in vivo squeaking is the stem design. However, it has not yet been possible to relate stem design to squeaking in deteriorating lubrication conditions. The purpose of this study was to determine critical friction factors for different stem designs. A hip simulator was used to measure the friction factor of a ceramic bearing with different stem designs and gradually deteriorating lubrication represented by evaporation of a volatile fluid lubricant. The critical squeaking friction factor was measured at the onset of squeaking for each stem. Critical friction was higher for the long cobalt chrome (0.32 ± 0.02) and short titanium stems (0.39 ± 0.02) in comparison with a long titanium stem (0.29 ± 0.02). The onset of squeaking occurred at a friction factor lower than that measured for dry conditions, in which squeaking is usually investigated experimentally. The results suggest that shorter or heavier stems might limit the possibility of squeaking as lubrication deteriorates. The method developed can be used to investigate the influence of design parameters on squeaking probability.
authors.affiliation: Tribology Research Institute, Southwest Jiaotong University, Chengdu, 610031, China.
authors.forename: Na
authors.initials: N
authors.lastname: Fan
authors.forename: Michael M
authors.initials: MM
authors.lastname: Morlock
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Bishop
authors.forename: Gerd
authors.initials: G
authors.lastname: Huber
authors.forename: Norbert
authors.initials: N
authors.lastname: Hoffmann
authors.forename: Michele
authors.initials: M
authors.lastname: Ciavarella
authors.forename: Guang X
authors.initials: GX
authors.lastname: Chen
authors.forename: Arne
authors.initials: A
authors.lastname: Hothan
authors.forename: Florian
authors.initials: F
authors.lastname: Witt
mesh_terms: D000096:Acetone; D019644:Arthroplasty, Replacement, Hip; D002516:Ceramics; D002858:Chromium Alloys; D020099:Coated Materials, Biocompatible; D017276:Friction / Q000502:physiology*; D006621:Hip Joint / Q000502:physiology*; D006622:Hip Prosthesis; D006801:Humans; D008153:Lubrication; D008422:Materials Testing; D009068:Movement / Q000502:physiology; D009622:Noise; D011474:Prosthesis Design; D013696:Temperature; D014025:Titanium
chemical_list: D002858:Chromium Alloys; D020099:Coated Materials, Biocompatible; D000096:Acetone; D014025:Titanium
keywords: ceramic bearing; critical friction; squeaking; stem design